WO2018234976A1 - Internal anticorrosive and abrasive resistant protection coating for steel pipes - Google Patents

Internal anticorrosive and abrasive resistant protection coating for steel pipes Download PDF

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Publication number
WO2018234976A1
WO2018234976A1 PCT/IB2018/054476 IB2018054476W WO2018234976A1 WO 2018234976 A1 WO2018234976 A1 WO 2018234976A1 IB 2018054476 W IB2018054476 W IB 2018054476W WO 2018234976 A1 WO2018234976 A1 WO 2018234976A1
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WIPO (PCT)
Prior art keywords
layer
coating
pipe
epoxy resin
thermoplastic
Prior art date
Application number
PCT/IB2018/054476
Other languages
French (fr)
Inventor
Adrian Andreani
Federico Noriega
Original Assignee
Patagonia Shale Services S.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US15/626,227 external-priority patent/US9958103B1/en
Priority claimed from US15/626,404 external-priority patent/US20180361720A1/en
Priority claimed from US15/626,276 external-priority patent/US10203063B2/en
Priority claimed from US15/626,538 external-priority patent/US20180361711A1/en
Application filed by Patagonia Shale Services S.A. filed Critical Patagonia Shale Services S.A.
Priority to EP18746285.8A priority Critical patent/EP3641953A1/en
Publication of WO2018234976A1 publication Critical patent/WO2018234976A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B32B15/085—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
    • B05D3/0218—Pretreatment, e.g. heating the substrate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
    • B05D7/146—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies to metallic pipes or tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/22—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to internal surfaces, e.g. of tubes
    • B05D7/222—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to internal surfaces, e.g. of tubes of pipes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/50—Multilayers
    • B05D7/56—Three layers or more
    • B05D7/58—No clear coat specified
    • B05D7/586—No clear coat specified each layer being cured, at least partially, separately
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B1/00—Layered products having a general shape other than plane
    • B32B1/08—Tubular products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B32B27/285—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42 comprising polyethers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B32B27/288—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42 comprising polyketones
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2202/00—Metallic substrate
    • B05D2202/10—Metallic substrate based on Fe
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2254/00—Tubes
    • B05D2254/04—Applying the material on the interior of the tube
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2420/00—Indexing scheme corresponding to the position of each layer within a multilayer coating relative to the substrate
    • B05D2420/01—Indexing scheme corresponding to the position of each layer within a multilayer coating relative to the substrate first layer from the substrate side
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2420/00—Indexing scheme corresponding to the position of each layer within a multilayer coating relative to the substrate
    • B05D2420/02—Indexing scheme corresponding to the position of each layer within a multilayer coating relative to the substrate second layer from the substrate side
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2420/00—Indexing scheme corresponding to the position of each layer within a multilayer coating relative to the substrate
    • B05D2420/03—Indexing scheme corresponding to the position of each layer within a multilayer coating relative to the substrate third layer from the substrate side
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2451/00—Type of carrier, type of coating (Multilayers)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/06—Coating on the layer surface on metal layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/26—Polymeric coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/714—Inert, i.e. inert to chemical degradation, corrosion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/752—Corrosion inhibitor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2597/00—Tubular articles, e.g. hoses, pipes

Definitions

  • the present invention is related to an internal anticorrosive and abrasive resistant protection coating for steel pipes.
  • the world market offers a great variety of coating options to protect the inner surface of pipes used for the transport of fluids from the effects of corrosion and erosion. Some, additionally, exhibit features that allow the reduction of friction and turbulence, thus, increasing the efficiency of flow.
  • these coatings exhibit adaptation to corrosive environments, resistance to various solvents and chemical products, as well as to cathodic detachment.
  • a very common kind of coating is cement mortar lining, which fulfills the standards set forth in ISO 4179 and AWWA C104 for use in water distribution systems and sewerage systems.
  • the ceramic epoxy coating for gravity-operated septic tanks and sewerage systems and the special inner coating for specific service conditions.
  • Inner cement lining is done by making the pipe rotate at high angular velocity coupled with vibration that produces a dense coating.
  • the high centrifugal speed allows the coating to become smooth, dense and perfectly compact.
  • the Hazen-Williams formula has determined that the coefficient of friction is 140 for cement linings and 150 for polyethylene and epoxy coatings.
  • Prior art shows a steel pipe inner coating made of high-density consolidated polyethylene. Also, prior art shows a steel pipe with an insulating inner coating and a fiber-filled thermoplastic liner placed inside a steel pipe.
  • prior art shows an inner coating for pipes made up of a highly heat-resistant TPU-Polyester lining which allows a nonwoven fabric to be saturated with an epoxy-amine resin and to be cured with steam or hot water.
  • thermoplastic coating made up of a solixane-based elastomer processable by heat fusion, a coating made of a thermoplastic material, and a thermoplastic coating applied to the inside of the pipe by injecting gas that pushes the material against the inner surface of the pipe.
  • the proposed invention also shows a yet-inexistent procedure in the prior art, whereby a layer of adhesive thermoplastic is applied between an epoxy adhesive and material of the plastic pipe so as to achieve a full adherence of the various components and steel of the metal pipe.
  • thermoplastic coating that adheres to the inside of pipes with such strength that it will counteract the strength of pressure drops present in oil and gas production pipelines.
  • the present invention includes an anticorrosive and abrasive resistant inner coating for steel pipes used to transport fluids.
  • the coating includes: a layer of epoxy resin having free hydroxyl groups, which is applied directly to the inside wall of the steel pipe; a layer of thermoplastic adhesive applied directly onto the layer of epoxy resin, the thermoplastic adhesive is anhydride modified polyolefin or acrylic acid modified polyolefin; and a layer of a plastic material directly applied onto the adhesive layer, the plastic material is a thermoplastic selected from one of the followings:
  • Figure 1 illustrates a cross section of the steel pipe 1 , which includes the coating as described in the present invention
  • Figure 2 shows a diagram which represents the chemical bonds formed through electron sharing by groups on the substrate and epoxy resin
  • Figure 3 shows a diagram that represents the chemical structure of the thermoplastic adhesive of the present invention.
  • Each of the component layers exhibits features that taken together afford a much superior protection compared to that of solutions in the prior art.
  • the present invention includes an inner anticorrosive and abrasive resistant coating for steel pipes used for the transport of fluids.
  • the coating includes:
  • thermoplastic adhesive applied directly onto the layer of epoxy resin
  • thermoplastic adhesive is anhydride modified polyolefin or acrylic acid modified polyolefin
  • plastic material is a thermoplastic selected from one of the followings:
  • the epoxy resin used in the present invention may be any resin that contains free hydroxyl groups.
  • the epoxy resin having free hydroxyl groups adheres to the metallic surface because of the chemical bonds formed through electron sharing by groups on the substrate and the free hydroxyl groups of the epoxy resin, the curing is accompanied by polarity change (See Fig 2).
  • Examples of preferred epoxy resins having free hydroxyl groups useful in the present invention are Epoxy, Phenolic Epoxy, Polyurethane Epoxy, and/ or Novolac (R) .
  • the thickness of the layer of epoxy resin is at least 30 microns, preferably between 30 and 250 microns.
  • the adhesive (3) is of the thermoplastic type and it allows a chemical bond with the epoxy of the first layer (2) so as to obtain full adherence to the metal.
  • thermoplastic adhesive used in the present invention may be Anhydride modified polyolefin or acrylic acid modified polyolefin, since the epoxy resins have free hydroxyl groups anhydride or acrylic acid adhesive that can react to form very strong bonds to the epoxy (See Fig 3).
  • Epoxy resin combines very low permeability to oxygen with excellent adhesion to properly prepared metallic surfaces and excellent resistance to cathodic disbondment. However, it is permeable to moisture, and is easily damaged by mechanical impacts. It is therefore beneficial to cover the epoxy resin with a layer of a polymer that is highly resistant to moisture permeation and resistant to impact damage.
  • Polyolefin coatings are widely used to protect metal pipelines, especially oil and gas pipelines, from both corrosion and mechanical damage.
  • the actual thermoplastic internal coating or polyolefins liners are not bonded to epoxy resin.
  • the present invention uses modified polyolefins that contain polar groups to bond to the epoxy resin layer.
  • modified polyolefin includes not only a polyolefin that is modified with an unsaturated carboxylic acid or an anhydride thereof, that is, a polyolefin copolymerized with the unsaturated carboxylic acid or the anhydride thereof, but also includes a blend of a polyolefin modified with the unsaturated carboxylic acid or anhydride thereof and an unmodified polyolefin.
  • the epoxy resin free hydroxyl-groups and the carboxylic acid dimer hydrogen bonding produces an epoxy resin-anhydride system.
  • the gelation phase of reaction exhibits rapid initial hydroxyl-anhydride reactions.
  • the acid or anhydride modified polyolefins of the invention are, in most cases, acid or anhydride modified polyethylenes, polypropylenes, or combinations thereof. Most preferably the polyolefins of the invention are acid or anhydride modified polypropylenes, acid or anhydride modified polypropylene derivatives, or mixtures of these.
  • the acid or anhydride modified polyolefin component of the invention may also be mixtures of acid or anhydride modified polyolefins with unmodified polyolefins.
  • the emulsion comprises several polyolefins, most of the polyolefins have grafted thereto at least one acid or anhydride.
  • the acids or anhydrides grafted on the polyolefins may be, in particular, ethylene-substituted carboxylic acids and/or polycarboxylic acids and/or acid anhydrides, such as, for example, maleic, acrylic, methacrylic, itaconic or citraconic acid (or anhydride).
  • acid or anhydride modified polyolefins of the invention are maleic anhydride modified polypropylenes.
  • Examples of preferred acid or anhydride modified polyolefin dispersions useful in the present invention are maleic anhydride grafted polypropylene dispersions such as Hydrosize XM- 10075, Hydrosize PP2- 01 , Hydrosize PPI-OI (all from Hydrosize Technologies, Inc., Raleigh, NC) and Michem Emulsion 91735 (available from Michelman, Inc., Cincinnati, OH).
  • maleic anhydride grafted polypropylene dispersions such as Hydrosize XM- 10075, Hydrosize PP2- 01 , Hydrosize PPI-OI (all from Hydrosize Technologies, Inc., Raleigh, NC) and Michem Emulsion 91735 (available from Michelman, Inc., Cincinnati, OH).
  • the thickness of the layer of the adhesive is at least 50 microns, preferably between 50 and 300.
  • thermoplastic adhesive (3) Onto the layer of thermoplastic adhesive (3) a fourth layer of plastic material is applied. This makes up the inner protection, which is very effective against abrasion and corrosion caused by fluids transported through steel pipes (1 ).
  • examples thereof include 12-Aminododecanoic acid lactam with the formula (C 12 H 2 3NO).
  • lactam poly 12-aminododecanoic acid is fused plastically with the adhesive of the layer of thermoplastic material (3) and the layer of epoxy resin (2) achieving complete adhesion to the metal.
  • the 12-Aminododecanoic acid lactam is also known as 12-
  • Aminododecanolactam 1 -Aza-2-cyclotridecanone; 12-Aminododecanoic acid lactam; 2-Oxododecamethylenimine; Azacyclotridecan-2-one; Cyclododecalactam; Dodecalactam, Dodecanoic acid; 12-amino-, lactam; Dodecanolactam; Dodecyllactam; Laurin lactam;Laurolactam; Lauryl lactam; omega-Dodecalactam; Dodecane-12-lactam.
  • the 12-Aminododecanoic acid lactam has low moisture uptake, excellent ductility, good electrical properties, and significant chemical and impact resistance.
  • the amide groups (-CO-NH-) of the 12-Aminododecanoic acid lactam forms hydrogen bridge bonds between the chains of the macromolecules, thereby substantially promoting crystallinity and increasing their strength, and resistance to chemicals.
  • 12-Aminododecanoic acid lactaml has the lowest amide group concentration of all commercially available monomers, giving it the lowest moisture absorption and higher stability.
  • the 12-Aminododecanoic acid lactaml has the following properties: high mechanical strength, elasticity and surface hardness;
  • the thickness of the layer of the 12-Aminododecanoic acid lactaml is between 1 mm to 8mm.
  • the modified polyolefin coating layer was strongly bonded onto the metal surface.
  • an aqueous solution containing an electrolyte such as brine or a solution of salt
  • the polyolefin coating layer peels off from the metal surface, and impact strength of the metal article deteriorates drastically.
  • the solution was to add a layer of polyethylene (4) directly over the thermoplastic layer (3). This affords an internal protection which is very efficient against abrasion and corrosion caused by fluids transported through the steel pipe (1 ).
  • Polyethylene is of low strength, hardness and rigidity, but has a high ductility and impact strength as well as low friction. Polyethylene is an excellent chemical resistance and includes nonpolar, saturated, high molecular weight hydrocarbons. In addition, Polyethylene absorbs almost no water.
  • thermoplastic materials Adhesive + Polyethylene
  • the plastic that makes up the third layer (4) is selected from a low, mid, or high-density polyethylene, or a linear one. In all cases, it is a layer of polyethylene coming from some form of polymerization of ethylene.
  • the polyethylene can be low, mid, or high-density, or lineal, with or without antioxidants, with or without additives, for UV-prevention.
  • the effectiveness of the bond is characterized by the density or specific gravity of the particular material used. Accordingly, when reference is made to a high density polyethylene material, it is meant to refer to those polyethylene materials having a density or specific gravity of from 0.941 to 0.965, and a melt index of from 0.2 to 5.
  • a medium density polyethylene material is one having a density or specific gravity in the range of from 0.926 to 0.940, and a melt index of from 0.3 to 22, while a low density polyethylene material is one having a density or specific gravity of from 0.910 to 0.925 and a melt index of from 0.3 to 22.
  • Linear low density polyethylene material is one having a density or specific gravity in the range of from 0.915 to 0.940 g cm "3 .
  • thermoplastic Polyethylene is classified as a "thermoplastic" in view of the way the plastic responds to heat. Thermoplastic materials become liquid at their melting point (1 10-130 degrees Celsius in the case of LDPE and HDPE respectively). A major useful attribute about thermoplastics is that they can be heated to their melting point, cooled, and reheated again without significant degradation. Instead of burning, thermoplastics like Polyethylene liquefy, which allows them to be easily [injection molded] and then subsequently recycled. By contrast, thermoset plastics can only be heated once (typically during the injection molding process).
  • the advantage of the above system lies in the fact that the epoxy coating provides good corrosion protection to the underlying steel pipeline, and the polyethylene layer provides excellent abrasion and impact resistance and acts as a complete barrier to the underlying pipe surface
  • the polyethylene layer once it has cured, provides a tough, flexible and impermeable protective coating.
  • the coating has a thickness between 1 mm to 5mm.
  • the modified polyolefin coating layer was strongly bonded onto the metal surface.
  • an aqueous solution containing an electrolyte such as brine or a solution of salt
  • the polyolefin coating layer peels off from the metal surface, and impact strength of the metal article deteriorates drastically.
  • PEEK is a fully aromatic, semi-crystalline thermoplastic polymer with a maximum crystallinity of 48 %. It is a member of the class of polyaryl ether ketones (PAEK) high performance polymers. PEEK has a glass transition point of 143 °C and a melting range of ca. 340 °C.
  • Characteristics of the polymer include a very high heat resistance and therefore service temperature, high rigidity, low water absorption, high hardness, good strength, low sliding friction, excellent chemical and hydrolysis resistance, hydrolysis resistance to steam, water, and sea water, low flammability, very low emission of smoke and toxic fumes during burning and its good electrical characteristics.
  • PEEK offers one of the highest resistances against radiation among polymers.
  • PEEK grades offer chemical and water resistance similar to PPS
  • PEEK PolyPhenylene Sulfide
  • PEEK can be used continuously to 480 °F (250 °C) and in hot water or steam without permanent loss in physical properties.
  • PEEK is a high strength alternative to fluoropolymers.
  • PEEK carries a V-0 flammability rating and exhibits very low smoke and toxic gas emission when exposed to flame.
  • the advantage of the above system lies in the fact that the fusion bonded epoxy coating provides good corrosion protection to the underlying steel pipeline, and the Polyether ether ketone layer provides excellent abrasion and impact resistance and acts as a complete barrier to the underlying pipe surface
  • the Polyether ether ketone layer once it has cured, provides a tough, flexible and impermeable protective coating.
  • the coating has a thickness of between 1 mm to 10 mm.
  • the modified polyolefin coating layer was strongly bonded onto the metal surface.
  • an aqueous solution containing an electrolyte such as brine or a solution of salt
  • the polyolefin coating layer peels off from the metal surface, and impact strength of the metal article deteriorates drastically.
  • the solution was to add a layer of polypropylene (4) directly over the thermoplastic layer (3).
  • the layers of adhesive and polypropylene are heated, the molecular structure of both changes from a crystal state to an amorphous state.
  • pressure is applied, the molecules of adhesive and polypropylene fuse and mix since they are both thermoplastic.
  • the molecules of both thermoplastic materials Adhesive + Polypropylene
  • the polypropylene can have isomeric form, either isotactic or syndiotactic, ranging from homopolymers, impact copolymers to random copolymers.
  • the thickness of the layer of the polypropylene is between 1 mm to 15 mm.
  • the epoxy resin layer (2) is applied onto the inner surface (1 a) of the steel pipe (1 ). Once the pipe has been burned (1 ) and later cleaned (abrasive blasting) with an abrasive material so as to eliminate contaminants, the inside surface (1 a) of the pipe (1 ) will be clean and ready for the epoxy resin (2) to be applied.
  • the steel pipe (1 ) Before applying the epoxy resin (2), the steel pipe (1 ) will be burned. In the burn-off step the temperature must be controlled so as not to alter the metallographic conditions of the steel pipe (1 ). For this reason, the burn-off temperature must not exceed 350 Q C. This temperature will easily eliminate oils, grease, and fuel residues that might be covering inside of the steel pipe (1 ). On the other hand, the applied temperature must not be lower than 100 Q C, since below that level the desired burn-off will not be achieved.
  • the abrasive blasting step seeks to prepare the inner surface of the steel pipe (1 ) by complementing the burn-off described in the previous step and, thus, improving the adherence of the epoxy resin (2).
  • the abrasive blasting is done with non- contaminating material, preferably using O 2 AI 3 grit.
  • the pipe (1 ) is heated at a temperature of between 120 Q C and 180 Q C, since this temperature improves the curing of the epoxy resin (2), which is applied at a later step before it completes its polymerization.
  • the heat is applied onto the exterior surface of said steel pipe (1 ).
  • the next step involves applying a layer of epoxy resin on the inner surface (1 a) of the steel pipe (1 ).
  • the epoxy resin can be applied in liquid, granular, or powder form.
  • thermoplastic adhesive (3) is applied directly onto the layer of the epoxy resin (2) while raising the temperature of the steel pipe, thus, achieving a chemical bond between said epoxy resin layer (2) and the thermoplastic adhesive layer (3).
  • said epoxy resin (2) will be cured.
  • the steel pipe 1 is heated from the outside, so that in both cases the temperature reaches the inner surface 1 a of said steel pipe (1 ) by conduction.
  • the temperature at which the steel pipe 1 is heated in the heating step depends on the thickness and diameter of the steel pipe 1 . Of course, it is closely related to the composition and the temperature of the product that will be transported.
  • the temperature at which the steel pipe is heated ranges between 180 Q C and 350 Q C.
  • the layer (4) containing 12-Aminododecanoic acid lactam, polyethylene, polyether ether ketone (PEEK); or polypropylene is pressed against the layer of thermoplastic adhesive by injecting a fluid (gaseous or liquid) at high pressure into the pipe, while the steel pipe (1 ) is heated from the outside, thus, achieving the fusion between said adhesive and said plastic.
  • a fluid gaseous or liquid
  • the level of adherence obtained is higher than 15.3 Kg/25 mm at a temperature of 20 Q C.

Abstract

The present invention includes an inner anticorrosive and abrasive resistant coating for steel pipes (1) used for the transport of fluids. The coating includes: a layer of epoxy resin (2) having free hydroxyl groups, which are applied directly to the inside 1 a of the steel pipe (1); a layer of thermoplastic adhesive (3) applied directly onto the layer of epoxy resin; and a layer of a plastic material (4) directly applied onto the adhesive layer, the plastic material is a thermoplastic selected from one of the followings:12-Aminododecanoic acid lactam with the formula (C12H23NO); polyethylene; polyether ether ketone; or polypropylene.

Description

INTERNAL ANTICORROSIVE AND ABRASIVE RESISTANT PROTECTION COATING FOR STEEL PIPES FIELD OF THE INVENTION
The present invention is related to an internal anticorrosive and abrasive resistant protection coating for steel pipes. BACKGROUND OF THE INVENTION
The world market offers a great variety of coating options to protect the inner surface of pipes used for the transport of fluids from the effects of corrosion and erosion. Some, additionally, exhibit features that allow the reduction of friction and turbulence, thus, increasing the efficiency of flow.
Among the alternatives to anticorrosive coatings, one can find those based on liquid epoxy; the epoxy coating is adhered by fusion and the special anticorrosive paints.
Among the main features of these coatings, they exhibit adaptation to corrosive environments, resistance to various solvents and chemical products, as well as to cathodic detachment.
The research on inner coatings, along with the technical and metallurgic evolution required by pipes and accessories, has resulted in the development of coating that satisfies all kinds of needs.
A very common kind of coating is cement mortar lining, which fulfills the standards set forth in ISO 4179 and AWWA C104 for use in water distribution systems and sewerage systems. The ceramic epoxy coating for gravity-operated septic tanks and sewerage systems and the special inner coating for specific service conditions.
Inner cement lining is done by making the pipe rotate at high angular velocity coupled with vibration that produces a dense coating.
The high centrifugal speed allows the coating to become smooth, dense and perfectly compact. The Hazen-Williams formula has determined that the coefficient of friction is 140 for cement linings and 150 for polyethylene and epoxy coatings.
Other anticorrosive and abrasive resistant protections include placing plastic liners inside the pipes. However, said liners are not adhered to the metal. They are simply attached at the ends of the pipe to avoid displacement.
Prior art shows a steel pipe inner coating made of high-density consolidated polyethylene. Also, prior art shows a steel pipe with an insulating inner coating and a fiber-filled thermoplastic liner placed inside a steel pipe.
Besides, prior art shows an inner coating for pipes made up of a highly heat-resistant TPU-Polyester lining which allows a nonwoven fabric to be saturated with an epoxy-amine resin and to be cured with steam or hot water.
There is a coating made up of a solixane-based elastomer processable by heat fusion, a coating made of a thermoplastic material, and a thermoplastic coating applied to the inside of the pipe by injecting gas that pushes the material against the inner surface of the pipe.
Even though all the known coatings in the field of technique yield the desired results for their specific purpose, the known coatings do not, unfortunately, include a plastic coating that can strongly adhere to pipes, so that it can withstand pressure drops of the magnitudes present in oil and gas production pipelines.
Nor does prior art show a coating that can make pipes impermeable to liquids and gases simultaneously.
In addition to solving the previous points, the proposed invention also shows a yet-inexistent procedure in the prior art, whereby a layer of adhesive thermoplastic is applied between an epoxy adhesive and material of the plastic pipe so as to achieve a full adherence of the various components and steel of the metal pipe.
Finally, neither is there in the state of the art, and the invention does describe this, a procedure that includes a step whereby a plastic pipe is pressed against the surface of the steel pipe, while simultaneously applying heat at a temperature higher than the point of softening of the thermoplastic material, but without damaging the material.
SUMMARY OF INVENTION
It is an object of the present invention to have a thermoplastic coating that adheres to the inside of pipes with such strength that it will counteract the strength of pressure drops present in oil and gas production pipelines.
It is another object of the revealed procedure that the inner coating of the steel pipe is impermeable to the transported liquids and gases.
It is another object of the present invention to provide a layer of thermoplastic adhesive between the epoxy layer and the material of the plastic pipe.
It is also an object of the present documentation to have a procedure including the steps to press the plastic pipe against the wall of the metal pipe while simultaneously applying temperature.
Finally, it is an object of this invention to have a steel pipe lined with an inner plastic pipe, and between said pipes there is a layer of adhesive and a layer of epoxy.
The present invention includes an anticorrosive and abrasive resistant inner coating for steel pipes used to transport fluids. The coating includes: a layer of epoxy resin having free hydroxyl groups, which is applied directly to the inside wall of the steel pipe; a layer of thermoplastic adhesive applied directly onto the layer of epoxy resin, the thermoplastic adhesive is anhydride modified polyolefin or acrylic acid modified polyolefin; and a layer of a plastic material directly applied onto the adhesive layer, the plastic material is a thermoplastic selected from one of the followings:
12-Aminododecanoic acid lactam with the formula (C12H23NO);
polyethylene;
polyether ether ketone; or
polypropylene
BRIEF DESCRIPTION OF DRAWINGS Figure 1 illustrates a cross section of the steel pipe 1 , which includes the coating as described in the present invention;
Figure 2 shows a diagram which represents the chemical bonds formed through electron sharing by groups on the substrate and epoxy resin; and
Figure 3 shows a diagram that represents the chemical structure of the thermoplastic adhesive of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
With the aim to make the present invention comprehensible so that it can be applied easily, a precise description of the preferred method for manufacturing will be presented in the following paragraphs. Said description includes a diagram illustrating the invention. Said description and diagram cannot be regarded in any way as limiting the invention. The components mentioned in the description can be selected among various equivalents, but without deviating from the principles of the invention set forth in the current documentation.
In the case described in the present documentation, it protects the steel pipe with a three-layer coating, which includes an epoxy resin and a plastic material with an in-between layer made up of an adhesive, which allows said three layers to bond and fuse with each other and the steel pipe.
Each of the component layers exhibits features that taken together afford a much superior protection compared to that of solutions in the prior art.
The present invention includes an inner anticorrosive and abrasive resistant coating for steel pipes used for the transport of fluids. The coating includes:
a layer of epoxy resin having free hydroxyl groups, which is applied directly to the inside of the steel pipe;
a layer of thermoplastic adhesive applied directly onto the layer of epoxy resin, the thermoplastic adhesive is anhydride modified polyolefin or acrylic acid modified polyolefin; and a layer of a plastic material directly applied onto the adhesive layer, the plastic material is a thermoplastic selected from one of the followings:
12-Aminododecanoic acid lactam with the formula (C12H23NO);
polyethylene;
polyether ether ketone; or
polypropylene
EPOXY RESIN
The epoxy resin used in the present invention may be any resin that contains free hydroxyl groups.
The epoxy resin having free hydroxyl groups adheres to the metallic surface because of the chemical bonds formed through electron sharing by groups on the substrate and the free hydroxyl groups of the epoxy resin, the curing is accompanied by polarity change (See Fig 2).
It will be understood that the curing phenomenon of epoxy resin compositions involves chemical linking between polymer chains and that this linking (or "cross-linking") mechanism is initiated almost immediately upon application of the epoxy resin upon a hot surface and continues as the epoxy resin composition melts, coalesces and gels.
Examples of preferred epoxy resins having free hydroxyl groups useful in the present invention are Epoxy, Phenolic Epoxy, Polyurethane Epoxy, and/ or Novolac(R).
The thickness of the layer of epoxy resin is at least 30 microns, preferably between 30 and 250 microns.
THERMOPLASTIC ADHESIVE In the preferred method for manufacturing described in the present documentation, the adhesive (3) is of the thermoplastic type and it allows a chemical bond with the epoxy of the first layer (2) so as to obtain full adherence to the metal.
The thermoplastic adhesive used in the present invention may be Anhydride modified polyolefin or acrylic acid modified polyolefin, since the epoxy resins have free hydroxyl groups anhydride or acrylic acid adhesive that can react to form very strong bonds to the epoxy (See Fig 3).
Epoxy resin combines very low permeability to oxygen with excellent adhesion to properly prepared metallic surfaces and excellent resistance to cathodic disbondment. However, it is permeable to moisture, and is easily damaged by mechanical impacts. It is therefore beneficial to cover the epoxy resin with a layer of a polymer that is highly resistant to moisture permeation and resistant to impact damage.
Polyolefin coatings are widely used to protect metal pipelines, especially oil and gas pipelines, from both corrosion and mechanical damage. Unfortunately, the actual thermoplastic internal coating or polyolefins liners are not bonded to epoxy resin. The present invention uses modified polyolefins that contain polar groups to bond to the epoxy resin layer.
It is to be understood that the term "modified polyolefin", as used in the present invention, includes not only a polyolefin that is modified with an unsaturated carboxylic acid or an anhydride thereof, that is, a polyolefin copolymerized with the unsaturated carboxylic acid or the anhydride thereof, but also includes a blend of a polyolefin modified with the unsaturated carboxylic acid or anhydride thereof and an unmodified polyolefin.
The epoxy resin free hydroxyl-groups and the carboxylic acid dimer hydrogen bonding produces an epoxy resin-anhydride system. The gelation phase of reaction exhibits rapid initial hydroxyl-anhydride reactions.
The acid or anhydride modified polyolefins of the invention are, in most cases, acid or anhydride modified polyethylenes, polypropylenes, or combinations thereof. Most preferably the polyolefins of the invention are acid or anhydride modified polypropylenes, acid or anhydride modified polypropylene derivatives, or mixtures of these. The acid or anhydride modified polyolefin component of the invention may also be mixtures of acid or anhydride modified polyolefins with unmodified polyolefins. Preferably, if the emulsion comprises several polyolefins, most of the polyolefins have grafted thereto at least one acid or anhydride. The acids or anhydrides grafted on the polyolefins may be, in particular, ethylene-substituted carboxylic acids and/or polycarboxylic acids and/or acid anhydrides, such as, for example, maleic, acrylic, methacrylic, itaconic or citraconic acid (or anhydride). Most preferably the acid or anhydride modified polyolefins of the invention are maleic anhydride modified polypropylenes.
Examples of preferred acid or anhydride modified polyolefin dispersions useful in the present invention are maleic anhydride grafted polypropylene dispersions such as Hydrosize XM- 10075, Hydrosize PP2- 01 , Hydrosize PPI-OI (all from Hydrosize Technologies, Inc., Raleigh, NC) and Michem Emulsion 91735 (available from Michelman, Inc., Cincinnati, OH).
The thickness of the layer of the adhesive is at least 50 microns, preferably between 50 and 300.
12-AMINODODECANOIC ACID LACTAM
Onto the layer of thermoplastic adhesive (3) a fourth layer of plastic material is applied. This makes up the inner protection, which is very effective against abrasion and corrosion caused by fluids transported through steel pipes (1 ).
Preferably, examples thereof include 12-Aminododecanoic acid lactam with the formula (C12H23NO).
The lactam poly 12-aminododecanoic acid is fused plastically with the adhesive of the layer of thermoplastic material (3) and the layer of epoxy resin (2) achieving complete adhesion to the metal.
The 12-Aminododecanoic acid lactam is also known as 12-
Aminododecanolactam; 1 -Aza-2-cyclotridecanone; 12-Aminododecanoic acid lactam; 2-Oxododecamethylenimine; Azacyclotridecan-2-one; Cyclododecalactam; Dodecalactam, Dodecanoic acid; 12-amino-, lactam; Dodecanolactam; Dodecyllactam; Laurin lactam;Laurolactam; Lauryl lactam; omega-Dodecalactam; Dodecane-12-lactam.
The 12-Aminododecanoic acid lactam has low moisture uptake, excellent ductility, good electrical properties, and significant chemical and impact resistance.
The amide groups (-CO-NH-) of the 12-Aminododecanoic acid lactam forms hydrogen bridge bonds between the chains of the macromolecules, thereby substantially promoting crystallinity and increasing their strength, and resistance to chemicals. 12-Aminododecanoic acid lactaml has the lowest amide group concentration of all commercially available monomers, giving it the lowest moisture absorption and higher stability.
The 12-Aminododecanoic acid lactaml has the following properties: high mechanical strength, elasticity and surface hardness;
low water absorption and water vapor permeability;
low thermal conductivity; and
good electrical insulation and dielectric strength.
The thickness of the layer of the 12-Aminododecanoic acid lactaml is between 1 mm to 8mm.
POLYETHYLENE
The inventor noted that the modified polyolefin coating layer was strongly bonded onto the metal surface. However, when the coating layer is contacted with an aqueous solution containing an electrolyte such as brine or a solution of salt, the polyolefin coating layer peels off from the metal surface, and impact strength of the metal article deteriorates drastically.
The solution was to add a layer of polyethylene (4) directly over the thermoplastic layer (3). This affords an internal protection which is very efficient against abrasion and corrosion caused by fluids transported through the steel pipe (1 ).
Polyethylene is of low strength, hardness and rigidity, but has a high ductility and impact strength as well as low friction. Polyethylene is an excellent chemical resistance and includes nonpolar, saturated, high molecular weight hydrocarbons. In addition, Polyethylene absorbs almost no water.
When the layers of adhesive and polyethylene are heated, the molecular structure of both changes from a crystal state to an amorphous state. When pressure is applied, the molecules of adhesive and polyethylene fuse and mix since they are both thermoplastic.
As they cool down, the molecules of both thermoplastic materials (Adhesive + Polyethylene), return to their crystal state, forming a homogeneous interface and acquiring the same resistance of each component material.
In the present case, the plastic that makes up the third layer (4) is selected from a low, mid, or high-density polyethylene, or a linear one. In all cases, it is a layer of polyethylene coming from some form of polymerization of ethylene.
The polyethylene can be low, mid, or high-density, or lineal, with or without antioxidants, with or without additives, for UV-prevention.
It has been found that the effectiveness of the bond is characterized by the density or specific gravity of the particular material used. Accordingly, when reference is made to a high density polyethylene material, it is meant to refer to those polyethylene materials having a density or specific gravity of from 0.941 to 0.965, and a melt index of from 0.2 to 5. A medium density polyethylene material is one having a density or specific gravity in the range of from 0.926 to 0.940, and a melt index of from 0.3 to 22, while a low density polyethylene material is one having a density or specific gravity of from 0.910 to 0.925 and a melt index of from 0.3 to 22. Linear low density polyethylene material is one having a density or specific gravity in the range of from 0.915 to 0.940 g cm"3.
Polyethylene is classified as a "thermoplastic" in view of the way the plastic responds to heat. Thermoplastic materials become liquid at their melting point (1 10-130 degrees Celsius in the case of LDPE and HDPE respectively). A major useful attribute about thermoplastics is that they can be heated to their melting point, cooled, and reheated again without significant degradation. Instead of burning, thermoplastics like Polyethylene liquefy, which allows them to be easily [injection molded] and then subsequently recycled. By contrast, thermoset plastics can only be heated once (typically during the injection molding process).
The advantage of the above system lies in the fact that the epoxy coating provides good corrosion protection to the underlying steel pipeline, and the polyethylene layer provides excellent abrasion and impact resistance and acts as a complete barrier to the underlying pipe surface The polyethylene layer, once it has cured, provides a tough, flexible and impermeable protective coating.
Advantageously the coating has a thickness between 1 mm to 5mm. POLYETHER ETHER KETONE (PEEK)
The inventor noted that the modified polyolefin coating layer was strongly bonded onto the metal surface. However, when the coating layer is contacted with an aqueous solution containing an electrolyte such as brine or a solution of salt, the polyolefin coating layer peels off from the metal surface, and impact strength of the metal article deteriorates drastically.
The solution was to add a layer of Polyether ether ketone (PEEK) (4) directly over the thermoplastic layer (3). This affords an internal protection which is very efficient against abrasion and corrosion caused by fluids transported through the steel pipe (1 ).
PEEK is a fully aromatic, semi-crystalline thermoplastic polymer with a maximum crystallinity of 48 %. It is a member of the class of polyaryl ether ketones (PAEK) high performance polymers. PEEK has a glass transition point of 143 °C and a melting range of ca. 340 °C.
Characteristics of the polymer include a very high heat resistance and therefore service temperature, high rigidity, low water absorption, high hardness, good strength, low sliding friction, excellent chemical and hydrolysis resistance, hydrolysis resistance to steam, water, and sea water, low flammability, very low emission of smoke and toxic fumes during burning and its good electrical characteristics. PEEK offers one of the highest resistances against radiation among polymers.
Using Peek as the last coat is good for the protection of the corrosion control coating against chemical and mechanical damage and also against effects of weathering.
PEEK grades offer chemical and water resistance similar to PPS
(PolyPhenylene Sulfide), but can operate at higher temperatures. PEEK can be used continuously to 480 °F (250 °C) and in hot water or steam without permanent loss in physical properties. For hostile environments, PEEK is a high strength alternative to fluoropolymers. PEEK carries a V-0 flammability rating and exhibits very low smoke and toxic gas emission when exposed to flame.
There are a lot of commercially available of PEEK products such as the obe produced by EVONIK by the commercial name VESTAKEEP PPEK or the one produced by Vitrex by the commercial name VITREX HT or VITREX ST among others.
The advantage of the above system lies in the fact that the fusion bonded epoxy coating provides good corrosion protection to the underlying steel pipeline, and the Polyether ether ketone layer provides excellent abrasion and impact resistance and acts as a complete barrier to the underlying pipe surface
The Polyether ether ketone layer, once it has cured, provides a tough, flexible and impermeable protective coating.
Advantageously the coating has a thickness of between 1 mm to 10 mm.
POLYPROPYLENE
The inventor noted that the modified polyolefin coating layer was strongly bonded onto the metal surface. However, when the coating layer is contacted with an aqueous solution containing an electrolyte such as brine or a solution of salt, the polyolefin coating layer peels off from the metal surface, and impact strength of the metal article deteriorates drastically.
The solution was to add a layer of polypropylene (4) directly over the thermoplastic layer (3). This affords an internal protection which is very efficient against abrasion and corrosion caused by fluids transported through the steel pipe (1 ). When the layers of adhesive and polypropylene are heated, the molecular structure of both changes from a crystal state to an amorphous state. When pressure is applied, the molecules of adhesive and polypropylene fuse and mix since they are both thermoplastic. As they cool down, the molecules of both thermoplastic materials (Adhesive + Polypropylene), return to their crystal state, forming a homogeneous interface and acquiring the same resistance of each of the component materials.
The polypropylene can have isomeric form, either isotactic or syndiotactic, ranging from homopolymers, impact copolymers to random copolymers.
The thickness of the layer of the polypropylene is between 1 mm to 15 mm.
The epoxy resin layer (2) is applied onto the inner surface (1 a) of the steel pipe (1 ). Once the pipe has been burned (1 ) and later cleaned (abrasive blasting) with an abrasive material so as to eliminate contaminants, the inside surface (1 a) of the pipe (1 ) will be clean and ready for the epoxy resin (2) to be applied.
Before applying the epoxy resin (2), the steel pipe (1 ) will be burned. In the burn-off step the temperature must be controlled so as not to alter the metallographic conditions of the steel pipe (1 ). For this reason, the burn-off temperature must not exceed 350QC. This temperature will easily eliminate oils, grease, and fuel residues that might be covering inside of the steel pipe (1 ). On the other hand, the applied temperature must not be lower than 100QC, since below that level the desired burn-off will not be achieved.
The abrasive blasting step seeks to prepare the inner surface of the steel pipe (1 ) by complementing the burn-off described in the previous step and, thus, improving the adherence of the epoxy resin (2). In the preferred method for manufacturing described, the abrasive blasting is done with non- contaminating material, preferably using O2AI3 grit.
Then comes a heating step whereby the pipe (1 ) is heated at a temperature of between 120QC and 180QC, since this temperature improves the curing of the epoxy resin (2), which is applied at a later step before it completes its polymerization. In the preferred method for manufacturing in the present documentation, in the step where the steel pipe is heated, the heat is applied onto the exterior surface of said steel pipe (1 ).
The next step involves applying a layer of epoxy resin on the inner surface (1 a) of the steel pipe (1 ). The epoxy resin can be applied in liquid, granular, or powder form.
Then a layer of thermoplastic adhesive (3) is applied directly onto the layer of the epoxy resin (2) while raising the temperature of the steel pipe, thus, achieving a chemical bond between said epoxy resin layer (2) and the thermoplastic adhesive layer (3). This makes the adhesive 3 come into close contact with the epoxy resin (2). Hence, in the step where temperature is raised, said epoxy resin (2) will be cured. The polymerization of the epoxy resin (2) and the fusion of the adhesive (3), which result from the step where temperature is raised to ensure a very strong chemical coupling, due to union of the carboxyl groups and the epoxy groups. As in the previous heating step, in the step where the temperature is raised, the steel pipe 1 is heated from the outside, so that in both cases the temperature reaches the inner surface 1 a of said steel pipe (1 ) by conduction.
The temperature at which the steel pipe 1 is heated in the heating step depends on the thickness and diameter of the steel pipe 1 . Of course, it is closely related to the composition and the temperature of the product that will be transported.
In the preferred method described in the present documentation, the temperature at which the steel pipe is heated ranges between 180QC and 350QC.
The layer (4) containing 12-Aminododecanoic acid lactam, polyethylene, polyether ether ketone (PEEK); or polypropylene is pressed against the layer of thermoplastic adhesive by injecting a fluid (gaseous or liquid) at high pressure into the pipe, while the steel pipe (1 ) is heated from the outside, thus, achieving the fusion between said adhesive and said plastic.
To determine the level of adherence to the metal, the inventors have conducted several trials following the CSA Standard Z 245.21 -06 (Canadian Standard Association), Peel Adhesion (hanging mass) for System B1 : >15.3 Kg/25 mm, 20° C.
The level of adherence obtained is higher than 15.3 Kg/25 mm at a temperature of 20QC.
Through the tests conducted, it is determined that the set of three layers on the inner surface of the steel pipe (1 ) can withstand sharp pressure drops at temperatures ranging from -30QC to 1 10QC, in accordance to the prescribed values in the autoclave trial defined in the NACE TM0185 specification.
In compliance with the specification, it is subjected during 20 days to pressures of up to 273 atm and temperatures of up to 1 10QC. The fluids used in the trial were kerosene, toluene, and formation water with 12% CINa and gaseous phase CO2.
Above, this document describes one possible method to produce the invention and the way the invention works. Additionally, this documentation is supplemented with a summary of the invention contained in the claims that are added below.

Claims

CLAIMS:
1 . An inner coating (10) providing anticorrosive and abrasive resistant protection for steel pipes (1 ) used for the transport of fluids, the coating includes:
a layer of epoxy resin having free hydroxyl groups (2) applied directly onto the inner surface 1 a of the steel pipe (1 );
a layer of thermoplastic adhesive (3) applied directly onto the layer of epoxy resin, the thermoplastic adhesive is anhydride modified polyolefin or acrylic acid modified polyolefin; and
a layer of a plastic material (4) directly applied onto the adhesive layer, the plastic material is a thermoplastic selected from one of the followings:
12-Aminododecanoic acid lactam with the formula (C12H23NO);
polyethylene;
polyether ether ketone; or
polypropylene.
2. The coating of claim 1 , wherein the coating has a level of adherence higher than 15.3 Kg/25 mm at a temperature of 20eC.
3. The coating of claim 1 , wherein it withstands sharp pressure drops at temperatures ranging from 30eC below zero to 1 10eC.
4. An internally lined steel pipe with an inner coating providing anticorrosion and abrasive resistant protection of the pipe, the coating includes:
a layer of epoxy resin having free hydroxyl groups (2) applied directly onto the inner surface 1 a of the steel pipe (1 );
a layer of thermoplastic adhesive (3) applied directly onto the layer of epoxy resin, the thermoplastic adhesive is anhydride modified polyolefin or acrylic acid modified polyolefin; and and a layer of a plastic material (4) directly applied onto the adhesive layer, the plastic material is a thermoplastic selected from one of the followings:
12-Aminododecanoic acid lactam with the formula (C12H23NO);
polyethylene;
polyether ether ketone; or
polypropylene.
5. A method to apply an anticorrosive and abrasive resistant inner coating to a pipe, the method comprising the steps of:
burning the pipe to a temperature between 100eC to 350eC;
cleaning an inner surface (1 a) of the pipe by using abrasive blasting; heating an exterior surface of the pipe to a temperature of between 120eC and 180eC;
applying while heating an epoxy resin layer (2) onto the inner surface (1 a) of the pipe (1 );
applying a layer of thermoplastic adhesive (3) directly onto the epoxy resin layer (2) while continuing heating the exterior surface of the pipe; and pressing against the layer of thermoplastic adhesive, while continuing heating the exterior surface of the pipe, a layer (4) containing 12- Aminododecanoic acid lactam, polyethylene, polyether ether ketone (PEEK).
PCT/IB2018/054476 2017-06-19 2018-06-18 Internal anticorrosive and abrasive resistant protection coating for steel pipes WO2018234976A1 (en)

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US15/626,404 US20180361720A1 (en) 2017-06-19 2017-06-19 Internal anticorrosive and abrasive resistant protection coating for steel pipes
US15/626,404 2017-06-19
US15/626,227 2017-06-19
US15/626,276 US10203063B2 (en) 2017-06-19 2017-06-19 Internal anticorrosive and abrasive resistant protection coating for steel pipes
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EP3683042A1 (en) * 2019-01-15 2020-07-22 Patagonia Shale Services S.A. Internal anticorrosive and abrasive resistant protection coating for pipes
CN112058612A (en) * 2020-09-07 2020-12-11 山东东宏管业股份有限公司 Novel double-layer plastic-coated steel wire and preparation method and application thereof
CN112762279A (en) * 2021-01-14 2021-05-07 温州赵氟隆有限公司 Processing method of plastic-coated pipeline with excellent adhesion

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